A user equipment (“UE”) may be configured with near-field communication (“NEC”) technology. NFC is a communications protocol operating at the unlicensed frequency band of 13.56 MHz. Two NFC-enabled devices may communicate securely at short ranges. For example, two NFC-enabled devices may exchange data by tapping the two devices together or bringing them into close proximity, or an NFC-enabled device may be used in a contactless payment system with an NFC-enabled payment terminal.
An NFC-enabled device includes a transmitter for generating an output signal and a receiver for demodulating a received signal. The NFC-enabled device may include a single antenna for transmitting the output signal and receiving the received signal. Thus, the transmission circuitry path from the transmitter to the antenna may comprise common circuitry with the receiving circuitry path from the antenna to the receiver.
The sharing of common transmit and receive circuitry may cause the output signal to leak into the receive chain as a leakage signal. Thus, the leakage signal may combine with the received signal to increase the signal power seen at the receiver input. This typically results in a decreased sensitivity for the receiver.
The range at which NFC-enabled devices may communicate depends on a variety of factors, including transmit power and receiver sensitivity. When a device is transmitting and receiving simultaneously an increase in carrier transmit power may cause an increase in carrier power leakage into the receive chain. This may degrade the receiver sensitivity and limit the communication range. Thus, a need exists for mitigating carrier leakage and improving the range at which NFC-enabled devices may communicate.